1. Technical Field
The present disclosure relates to a device and a method for measuring the no-load voltage of a battery.
2. Discussion of the Art
Some electronic devices are powered by a battery. This is for example true for cell phones, laptop computers, tablet computers, video cameras, photo cameras, etc. For the proper operation of the electronic device, it is desirable to accurately determine the battery charge rate. The battery charge rate can be determined from the measurement of the no load voltage across the battery. The no-load voltage is the voltage across the battery substantially in the absence of electronic components connected to the battery, except for the measurement device, causing the battery charge or discharge.
However, when the battery powers the electronic components of the electronic device or when it is being charged by a power source connected to the electronic device, the voltage across the battery is generally different from the no-load voltage. In this case, the measured voltage must be corrected, which causes an inaccuracy of the charge rate thus determined.
Generally, the electronic device comprises a device for measuring the voltage across the battery just after the connection of the battery to the electronic device. Indeed, at this time, all the electronic components of the electronic device are generally turned off and no power source is connected to the electronic device, so that the measured voltage is equal to the no-load voltage of the battery. The measurement device converts the analog signal into digital data which are stored in a memory. The measurement operation may last for several hundreds of milliseconds. After the full start of the electronic device, the electronic device processing unit, for example, a microcontroller which controls the main functions of the electronic device, can read the value stored in the memory of the measurement device to determine the battery charge rate.
The measurement device converts the analog signal into digital data which are stored in a memory. The finally-measured voltage may then be different from the no-load voltage.
To decrease risks of battery use before the end of the measurement, a possibility is to decrease the duration of the battery voltage measurement operation after the connection of the battery to the electronic device. This duration can be decreased by decreasing the accuracy of the digital data obtained at the analog-to-digital conversion step. However, this is not compatible with the current tendency, which is to increase the accuracy of the battery charge rate determination.
There thus is a need to decrease risks for the battery voltage measurement on connection of a battery to an electronic device not to correspond to the no-load voltage of the battery, without decreasing the measurement accuracy.